The present invention relates to a power supply for providing high voltage power from a low voltage source. The present invention can be manufactured so as to have a thin profile (less than 0.25 inch in width) and therefore is particularly well-suited for use as a power supply for a flat screen CRT (cathode ray tube).
Although the general concept of providing power conversion is known, the recently developed technology of flat screen CRTs has presented a greater need for power conversion circuitry capable of providing high voltage power from a low voltage source (e.g., 8,000 volts from a 5 volt source). In order to maximize the compactness of such flat screen CRTs, it is important that their power supplies also be compact. Further, in the highly competitive market for consumer electronics, it is important that the power supply be constructed at the lowest cost possible and therefore in a manner which permits automated manufacturing.
As is generally known by those skilled in the art, zero voltage switching of switches in electrical circuitry has been used to reduce the losses associated with opening and closing the switches. Thus, the switches have been operated in such a manner as to improve the efficiency of the electrical circuitry which incorporates the switches.
To increase the output power of conventional power supplies, two or more converters, including two or more transformers, two or more constant current sources and associated circuitry for each transformer, can be connected together. Alternatively, a power supply with increased output power has been provided by incorporating a larger transformer design. Thus, an increase in output power necessitates a much larger power supply design because of the increased number of components and/or a large transformer. The cost of manufacture is therefore increased and possibility of automated construction becomes limited. Moreover, if two or more converters are connected together to obtain an increased maximum output power, the multiple converters will often detrimentally interact with one another so that one or more of the transformer cores saturates.